Chryseobacterium tructae sp. nov., isolated from rainbow trout (Oncorhynchus mykiss)

Three pale-orange bacteria (strains 1083-08, 1084-08T and 1095B-08) were isolated from diseased rainbow trout. The isolates were Gram-staining-negative, catalase- and oxidase-positive, rod-shaped cells. Analyses of their 16S rRNA gene sequences confirmed their adscription to the genus Chryseobacterium. The three isolates shared 100% 16S rRNA gene sequence similarity and 98.5% similarity with Chryseobacterium indologenes CCUG 14556T, being the closest phylogenetically related species. Genomic DNA–DNA hybridization similarity values between the three isolates were 94–100% and 2–39% between strain 1084-08T and the type strains of other related Chryseobacterium species, confirming that the isolates represent a novel species within the genus Chryseobacterium. The DNA G+C content of the species was 33.6–36.1 mol%. The predominant respiratory quinone of strain 1084-08T was MK-6 and the major fatty acids were iso-C15:0, iso-C17:1ω9c, iso-C17:0 3-OH and C16:1ω6c. The isolates were distinguished from related Chryseobacterium species by a number of phenotypic properties. Based on the phenotypic, genotypic and phylogenetic findings, it is proposed that the new isolates from rainbow trout be classified as a new species of the genus Chryseobacterium, with the name of Chryseobacterium tructae sp. nov. The type strain is 1084-08T (=CECT 7798T = CCUG 60111T).